Question

The value of mean in a t or a z distribution is __. a. 0 b. 0.5 c. 1 d. problem specific 2. For the interval estimation of µ when σ is assumed known, the proper distribution to use is the . a. z distribution b. t distribution with n degrees of freedom c. t distribution with n-1 degrees of freedom d. t distribution with n-2 degrees of freedom 3. It is known that the variance of a population equals 1,936. A random sample of 121 has been taken from the population. There is a 0.95 probability that the sample mean will provide a margin of error of _(Hint: Error = ZSx/ √n). a. 7.84 or less b. 31.36 or less c. 344.96 or less d. 1,936 or less 4. A random sample of 144 observations has a mean of 20, a median of 21, and a mode of 22. The sample standard deviation is known to equal 4.8. The 95% confidence interval for the population mean is _(Hint: C.I. = X̄ -/+ ZSx/ √n). a. 15.2 to 24.8 b. 19.2 to 20.8 c. 19.216 to 20.784 d. 21.2 to 22.8 5. The manager of a grocery store has taken a random sample of 100 customers. The average length of time it took these 100 customers to check out was 3.0 minutes. It is known that the standard deviation of the checkout time is one minute. The standard error of the mean equals _____________(Hint: S. E. = Sx/ √n). a. 0.001 b. 0.010 c. 0.100 d. 1.000

          The value of mean in a t or a z distribution is ________.
a. 0
b. 0.5
c. 1
d. problem specific

2. For the interval estimation of µ when σ is assumed known, the proper distribution to use is the __________.
a. z distribution
b. t distribution with n degrees of freedom
c. t distribution with n-1 degrees of freedom
d. t distribution with n-2 degrees of freedom

3. It is known that the variance of a population equals 1,936. A random sample of 121 has been taken from the population. There is a 0.95 probability that the sample mean will provide a margin of error of _________(Hint: Error = Z*Sx/ √n).
a. 7.84 or less
b. 31.36 or less
c. 344.96 or less
d. 1,936 or less

4. A random sample of 144 observations has a mean of 20, a median of 21, and a mode of 22. The sample standard deviation is known to equal 4.8. The 95% confidence interval for the population mean is _________(Hint: C.I. = X̄ -/+ Z*Sx/ √n).
a. 15.2 to 24.8
b. 19.2 to 20.8
c. 19.216 to 20.784
d. 21.2 to 22.8

5. The manager of a grocery store has taken a random sample of 100 customers. The average length of time it took these 100 customers to check out was 3.0 minutes. It is known that the standard deviation of the checkout time is one minute. The standard error of the mean equals _________________(Hint: S. E. = Sx/ √n).
a. 0.001
b. 0.010
c. 0.100
d. 1.000

Added by Isabel T.

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